Nano composites involve many aspects of technology and have a wide variety of production processes available. In brief, the processes for producing nano composite can be classified into four groups: directly mixing metallic nano particles with polymer(s); forming metallic nano particles in a polymer matrix; polymerizing a polymer from monomer(s) in the presence of metallic nano particles; simultaneously forming metallic nano particles and a polymer. In the processes for preparing nano composite, the most crucial issue involves an effective control on the dimensions of the metallic nano particles per se in order to ensure that at least one dimension of a composition phase in the composite is within the range of a nano dimension, and then care is taken to control the aggregation of nano particles. In general, a surfactant, a metal salt, and a reducing agent are used in a chemical reduction process for producing nano particles. The types of applicable reducing agents include: hydrazine, sodium borohydride, hydrogen, etc. A typical chemical reduction process for producing nano particles comprises dissolving a surfactant in a liquid phase; adding and mixing metal ions in the liquid phase; and adding a reducing agent into the resulting mixture to reduce the metal ions into nano particles.
U.S. Pat. No. 6,855,749 discloses a nano-structured composite, which is prepared by blending a nanoscale filler with a matrix. Said nanoscale filler can be Ba, Bi, Cs, etc. Said matrix can be poly(acrylic acid), PAA. The method disclosed in this patent has a difficulty in uniformly distributing the nanoscale filler in the matrix, and is unable to adhere most metallic nano particles on the surface of the matrix.
U.S. Pat. Nos. 5,115,036 and 5,064,879 use a copolymer with a molecular weight of 5,000˜50,000, which is copolymerized from ethylene and aminoalkyl acrylate, and is modified to have different terminal functional groups with different electronegativities to chelate different metal ions. However, after chelation of the metal ions, the metal ions are liable to separate from a polymer matrix.
S. Hahakura, Journal of Crystal Growth, Vol. 237, pp. 1942-1945, 2002, discloses a process, which comprises dissolving a surfactant SDS (sodium dodecyl sulfate) in an aqueous solution to form micelles; using such a micelle structure as a template and introducing platinum ions into the micelles; and introducing hydrogen to reduce platinum ions into nano particles.
Kazutaka Hayakawa, Langmuir, Vol. 19, pp. 5517-5521, 2003, discloses a process, which comprises using a dendrimer as a matrix; dissolving HAuCl4 into a polymer emulsion; and using laser to reduce metal ions into nano particles. The dendrimer has a dispersion effect during the process of reducing metal ions into metallic nano particles. The formation of dendrimer also has an absolute effect on the particle size and the dispersion of the nano particles. Meanwhile, the dendrimer can be used to control the size and dispersion of the nano particles formed.